Tuesday, July 24, 2007

Out on a Limb as Promised-Black and White Moths

The above site explains better than my tired brain is functioning. What this demonstrates is that although evolution is taught as a fact this being, one example used in schools to teach it, it is only one theory and not very well supported one in science as some people seem to think. I was taught that the black/white moths of the industrial revolution was proof of evolution. I was taught this in high school even though there were huge doubts about the work before I was old enough to be in school.

Industrial Melanism. In 1959 Bernard Kettlewell published his work on the peppered moth as the "consummation and confirmation" of evolution. His work, and the famous photograph of the black and white forms of this moth on the lichen-covered trunk of a tree, have appeared in virtually every biology textbook as definitive evidence of evolution. The story began in England at the time of the Industrial Revolution where it was noted that as the tree trunks became blacked by industrial soot, the white form of the moth, Biston betularia, declined in numbers while the black form proliferated. Later in this century, when anti-pollution laws were introduced, the tree trunks became white and the moth population shifted back from predominately black to white. Kettlewell believed that the birds ate those moths that could easily be seen as they rested on the tree trunk. This shift in population was real but to this day no one really knows the mechanism. As early as 1975 doubts were expressed in Kettlewell's explanation because it was known that there were major problems but nothing was said in the textbooks. In 1998 Michael Majerus published a scholarly work titled Melanism: Evolution in Action in which these problems were spelled out. The birds were not the principal predator since they fly during the day when the moths are well hidden; researchers do not know where they hide. The moths do not rest on tree trunks but Kettlewell assumed they did and glued dead moths to the trunks, hence the photograph. The same population shift has occurred in an identical population of moths in Michigan where there had been no industrial pollution. Kettlewell's work is now highly suspect. He had simply observed a shift in population and is no more evidence for evolution than a shift in population of Caucasian and Black people.

1 comment:

crazylady said...

Um teacher, may I be excused to use the bathroom?

I have no idea what the net outcome of that moth seminar was supposed to tell me. Evolution, no evolution? Big bang?
I have a headache.

Tired academic.